Glass polyalkenoate cements (GPC) (also referred to as glass ionomer cements) are frequently used in dentistry as restorative and luting agents. GPCs are theoretically attractive for other clinical uses, such as orthopedics, because they set with a negligible exotherm. This is important because materials which generate heat upon setting can lead to thermal necrosis of adjacent healthy tissue. Additionally, GPCs bond with hydroxyapatite (present in both teeth and bones) and thus the set GPC is less likely to loosen over time. Finally, GPCs can be modified to release therapeutically beneficial ions over time. However, conventional GPCs are based on aluminosilicate glasses which are contraindicated in orthopedics as release of Al3+ in vivo leads to significant adverse effects for the patient. Fatal aluminum-induced encephalopathy, impaired osteoblastic function and hindered bone mineralization have been reported when using GPCs that include aluminum. GPCs free of aluminum have been attempted but those materials were not suitable as they set too quickly and did not provide sufficient handling time prior to setting to be able to deploy them. Some materials that did have longer handling times before setting had lower mechanical strength and thus were unsuitable for that reason.
What is needed are new GPCs for orthopedic applications that do not release aluminum ions but whose characteristics allow sufficient time to handle the material prior to setting and deliver sufficient mechanical strength.